Emission computed tomography (ECT) allows us to obtain pictorial data (e.g., axial transverse images of the brain) as well as dynamic functional data (such as regional cerebral glucose consumption rate (mg/min/100gm of brain substance), measurements of the storage, degradation and turnover of tagged metabolites, follow-through of the movement of the CSF in the deep CSF intracranial cavities). Two groups of radiopharmaceuticals may be used for ECT; 1) single photon, and 2) positron emitters. The unique property of ECT is that it may provide physiologic information not available with any other imaging procedures.